1. Field of the Invention
The present invention relates to a titanium-mica composite material. More specifically, it relates to a titanium-mica composite material suitable for use as a colorant or pigment providing colored pearl gloss in, for example, cosmetics, paints, printing inks, plastics, ornaments, daily necessities, fiber goods, and ceramics and also suitable for use as a conductive material in, for example, conductive layers and recording layers in recording papers and antistatic materials. The titanium-mica composite material according to the present invention exhibits excellent color tone (e.g., chroma and brightness), good consistency of an appearance color and an interference color, excellent stability, safety, light resistance, acid resistance, alkali resistance, solvent resistance, and heat resistance.
2. Description of the Prior Art
As is well known in the art, conventional titanated mica pigments used in, for example, the cosmetic field comprise very thin mica flake and a titanium dioxide layer formed thereon, as disclosed in Japanese Standard of Cosmetic Ingredient Supplement II, page 54 to 57 (published on 1982 YAKUJINIPPOU SHA. These conventional titanated mica pigments have pearl gloss and various interference colors. These titanated mica pigments are generally prepared as dislosed in Japanese Examined Patent Publication (Kokoku) No. 43-25644 by hydrolyzing an aqueous solution of the inorganic acid salt of titanium (e.g., titanyl sulfate) in the presence of mica to deposit hydrous titanium oxide on the surface of mica, followed by heating, although these titanated mica pigments can also be prepared by a vacuum deposition method. As the starting mica, muscovite is generally used, but biotite or other mica can also be used. The mica is previously subjected to aqueous grinding and sifting to obtain powder particles having a uniform particle size. The resultant titanated mica pigments exhibit various interference colors, depending upon the thickness of the titanium dioxide layer coated on the surface of the mica. The interference colors are generally silver when the titanium dioxide content is 10% to 26% by weight, gold when the titanium dioxide content is 26% to 40% by weight, red, blue, and green when the titanium dioxide content is increased from 40% by weight to 50% by weight, and higher order interference colors when the titanium dioxide content is 50% to 60% by weight. The correlations between the interference color and the thickness of the titanium dioxide layer coated on the surface of the mica are shown in Table 1.
TABLE 1 ______________________________________ Geometrical thickness (m.mu.) Interference color of TiO.sub.2 ______________________________________ Silver 20-40 Pale gold 40-90 Gold 40-90 Red 90-110 Purple 110-120 Blue 120-135 Green 135-155 Second order gold 155-175 Second order purple 175-200 ______________________________________
The conventional titanated mica pigments thus prepared have pearl gloss and various interference colors. However, the appearance colors thereof are always near or close to white and no pigments having bright appearance colors in agreement with the interference colors are obtained.
Various kinds of color pigments such as iron oxides, ferric ferrocyanide, chromium oxides, carbon black, and carmine have been heretofore incorporated into the above-mentioned titanated pigments to obtain various colored appearance. However, the various properties (e.g., stability, safety, light resistance, acid resistance, alkali resistance, solvent resistance, and heat resistance) of these colored titanated mica pigments largely depend upon the properties of the color pigments incorporated thereinto. For example, blue titanated mica pigments containing ferric ferrocyanide result in undesirable color fading in an alkaline solution. Red titanated mica pigments containing carmine result in color fading and deterioration against light. Furthermore, black titanated mica pigments containing carbon black and green titanated mica pigments containing chromium oxides have possible disadvantages from the safety point of view since the carbon black may include carcinogenic 3,4-benzpyrene as an impurity and Cr.sup.6+ has oral toxicity. Furthermore, the colored titanated mica pigments containing the color pigments cause color segregation or foreign odor generation in a solvent or various compositions (e.g., cosmetics) since the color pigments are incorporated.
The present inventor previously found that colored titanated mica pigments having bright color tone and pearl gloss and excellent safety, stability, light resistance, acid resistance, alkali resistance, solvent resistance, and heat resistance, which are equivalent to or superior to those of the above-mentioned titanated mica pigments or colored titanated mica pigments can be obtained by coating the surface of mica powder particles with a low oxide of titanium or a mixture of titanium dioxide and a low oxide of titanium (see Japanese Unexamined Patent Publication (Kokai) No. 59-126468.